Magnetic tools



Ju y 16, 1968 G. B. STILLWAGON, JR 3,392,767

MAGNETIC TOOLS Filed NOV. 15, 1965 FIG-4 INVENTOR.

GEORGE B.STILLWAGON,JR.

ATTORNEYS United States Patent 3,392,767 MAGNETIC TOOLS 1 1GeorgeBhStillwagon, Jr., Dayton, Ohio, assignortov Gardner Denver,Company, Dayton, Ohio, a corporation of Delaware ,Filed'Nov'. 15, 1965,Ser. No. 507,916

9 Claims. (Cl. 145-50) T his, invention relates to driving. tools andmore particularly to such tools which incorporate a permanent magnet forpicking up and retaining fastening devices to be driven by the tool.

Magnetic pick up screw drivers, sockets, and the like are useful inholding and retaining a fastener to be driven, in order to free theoperators .hands of this task while positioning the fastener accuratelyin relation to the fastener accuratelyin relation to the driver, as inassembly lineoperations. However, the permanent magnet structure in suchtools frequently imposes limitations on the design ofvthe tools and hasresulted, in some instances, in substantially increased costs ascompared to a conventio'na l tool. For example, in screw driven bits,the magnet has frequently been positioned within thetool holder axiallybehind the bit making relatively ineflicient use of the magneticmaterial. In bolt clearance sockets, where the magnet 'is received andmounted for axial movement within the socket, it was commonly necessaryto shield themagnet with a hard nonmagnetic alloy, such as brass,toprevent the magnet from shorting out on the tool body. Such brasssleeves imposed additional limitation in design as well as addedexpense.

The magnetic tools of the present invention incorporate a sheet-likemagnetic material which is magnetically polarized through its thickness.In other words, the present invention incorporates magnetic materialwhich is thickness-oriented, and which is suitably associated with thetool topro'vide concentric or spaced annular poles, providing efficientuse of the magnetic material in a compact tool construction.

It is accordingly an important object of the present invention toprovide a magnetic tool in which there is formed spaced-apart concentricpole pieces and between which thereis a strip of thickness-orientedmagnetized material.

A more particular object of this invention is the provision of amagnetic tool, as outlined above, in which one of the pole pieces is anannular, concentric sleeve orthe like, and in 'which the tool-bodyitself may comprise one of the pole pieces.

Accordingly, it is an object of this invention to provide an improvedmagnetic tool construction which may be utilized in a wide 'variety offorms including but not limited to sockets for driving nuts, sheet metalfasteners, an d'the like, and screw driver bits including but notlimited to drivers for cruciform-slotted screws, and ordinary screws.

Another object of this invention is the provision of a magnet assemblywhich is adapted for retaining fasteners in driving relation to adriving tool and the like, in which the assembly is formed with innerand outer spaced 3,392,767 Patented July 16, 1968 apart pole piecesdefining an annular space therebetween, and an annularthickness-oriented magnet is received in the space between a pole piece.f

These and other objects and advantages of the present invention willbecome apparent from the following description, the accompanyingdrawings and the'appended claims.

In the drawings:

FIG. 1 is a longitudinal section through a drive socket constructedaccording to this invention;

FIG. 2-is a transverse section through the socket taken generally alongthe line 2--'2' of FIG. 1; 1'

FIG. 3 is a'perspective view of a typical strip of thickness-orientedmagnetic material used in this invention prior to forming or shaping;

"FIG.- 4 is a perspective view of the material of FIG. 3 after it hasbeen shaped into cylinder;

'FIG. 5 is an elevational view of a screw driver bit con-' structedaccording to this'invention and showing-atypical fastener to be retainedthereon;

FIG. 6 is an enlarged longitudinal section through the magnetic assemblyof FIG. 5;

FIG. 7 is a transverse section taken generally along the lines 77 ofFIG. 6;

FIG. 8 is an elevational view of a further embodiment of the inventionas applied to a smaller screw driver bit;

FIG. 9 is an enlarged longitudinal section through the magnetic assemblyof FIG. 8 with the bit shown in elevation;

FIG. 10 is a further partial longitudinal section of the invention asapplied to a screw driver, showing the screw driver elevation; and

FIG. 11 is a modification of a portion of the structure shown in FIG. 10particularly adapted for retaining fasteners of small size.

Referring to the figures of the drawings which illustrate preferredembodiments of the invention, a magnetic pick up socket 10 is shown inFIGS. 1 and 2 as having a body 11 of generally tubular configuration.The socket shown in FIGS. 1 and 2 is of the type known as a clearancesocket, since it provides an opening to receive the threaded end of abolt while a fastener is being driven on the bolt. Accordingly, the body11 is formed with a forward end 12 and a rearward end 13 and a generallycylindrical bore 14. The forward end 12 is formed with a non-circularoutline which, in this case, is shown as hexagonal. The rearward end 13is shown as forming a square drive socket 15, adapted, for instance, tobe received on the square shank of a driver.

The socket includes forming a pair of spaced-apart, generally annularand axially extending pole pieces. In this embodiment, the body 11 formsone of the pole pieces, and a steel sleeve 18 received in the bore 14forms the other pole piece. As shown in FIGS. 1 and 2, the pole piecesformed by the body 11 on the one hand, and by the sleeve 18 on theother, define an annular space therebetween within which is received astrip 20 of thickness-oriented magnetized material, such as as shown inFIGS. 3 and 4.

The magnetized material is preferably a rubber bonded barium ferritecomposition which has magnetic properties similar to those displayed byisotropic barium ferrite sin tered magnets. A suitable material for thispurpose is disclosed in US. Patent No. 3,211,966 and the types I and I-Hsold under the tradename of Plastiform by Leyman Corporation, 5178Crookshank Road, Cincinnati, Ohio.

The characteristic feature of the material 20 is that it is normallymagnetized through the thickness, as distin guished from magnets inwhich the poles are formed at the longitudinal ends. Accordingly, themagnetic properties of this material may be considered as being thickv 3ness oriented. Since the bonding material is an elastomeric, such asrubber, the material may be formed into a cylinder such as shown in FIG.4. This is the shape which the material of the magnetassumes when it ispressed into the bore 14 between the sleeve 18 and the body 11,substantially as shown in FIG. 2.

Preferably, the strip making up the magnet 20 is formed of such a lengthas to form a complete cylinder when encapsulated within the tool.However, it is within the scope of this invention to employ, instead,segments of a cylinder comprising the magnetic material 20 between theannular pole pieces.

The forward end 23 of the magnet 20 is shown as being slightly recessedinwardly of the axial end of the sleeve 18. Also, the axial end 24 ofthe sleeve is proportioned in the socket opening 12 so that it comesinto physical contact with a fastener received within the socket. Sincethe annular socket body 11 at the socket opening 12 forms one of thepoles of the magnet, and since the end 24 of the sleeve 18 forms theother, it will be seen that when a fastener is received in the socket,it closes the magnetic space between the poles, resulting in anefficient and powerful retaining force on the fastener. The axialopening 25 formed within the sleeve 18 defines a clearance space throughwhich the end of a bolt may be received while the fastener is beingdriven thereon.

It will be seen from this embodiment that there is no relative movementbetween the magnetic assembly and the body of the tool. Once themagnetic assembly has been positioned in the bore 14, it becomes apermanent part of the tool. Further, all need for brass sleeves orbushings of other non-magnetic material and magnet positioning springsare eliminated.

FIGS. 5-7 show the invention applied to a screw driver bit. In thisembodiment, there is shown a bit which is formed from hexagonal stockand has a rear driven portion 31, an intermediate body portion 32 anddriving head 35. The driving head 35 may be formed with driving wings36, as shown in FIG. 5, to be received within the slotted recesses of afastener 38.

In this embodiment, an integral magnet assembly is shown as beingreceived on the intermediate or central portion 32 of the bit 30. Thismagnet assembly again comprises a pair of spaced annular pole piecesincluding an inner sleeve 42 which is proportioned to be received overthe bit 30, and an outer sleeve 44. The outer sleeve 44 is formed with arearward inwardly turning end or rim 45 defining an axial opening 46.

The inner sleeve may be recessed at the rearward end thereof asindicated at 48 to receive snap rings 49 which engage the body of thebit 30. As shown in FIG. 6, the axial extent of the recess 48 is such asto permit limited axial movement of the assembly 40 with respect to thesnap rings 49, so that the magnet assembly may align itself on the bit30 in position to contact the fastener 38. This provision for suchlimited axial movement of the assembly provides a means for compensatingfor variations in the length of the recesses in the fasteners, and forthe wear of the tip 36 of the bit, while always assuring direct contactof the terminal ends 50 and 51 of the sleeves 42 and 44 with thefastener 38.

Again, as described above, a strip of thickness oriented magnetizedmaterial 20 is formed in the annular space defined between the sleeves42 and 44, and forms opposite magnetic poles at the ends 50 and 51.Since the ends 50 and 51 come into full contact with the head of thefastener 38, and since the construction of the magnet assembly is suchthat there is a minimum of leakage between the pole pieces, thereresults a highly efficient use of the magnetic force of the material 20resulting in a compact and durable magnet assembly.

The embodiment shown in FIGS. 8 and 9 is somewhat similar to that ofFIGS. 5-7 except that this embodiment is particularly adapted for usewhere compact size is desired. Accordingly, there is shown a screwdriver bit which. is formed with a hexagonal driven portion 61 and agenerally cylindrical driving end 62 of substantially reduced diameter,such as for driving relatively small screws. In this embodiment, themagnet 20 is formed in the shape of a cylinder and is received directlyon the cylindrical surface of the bit end 62 and is retained orencircled by a sleeve 65.

The sleeve 65 has a forward tapered end 66 which may be rolled to reducethe crosssectional size of the forward end. However, it is importantthat the forward end 66 does not contact the bit and an annularclearance 67 has been provided to prevent shorting of the magnetic fluxpath.

In the embodiment of FIGS. 8 and 9, the driving end of the bit 60becomes one of the pole pieces, and the sleeve 65 becomes the other polepiece. This embodiment has been found to be highly efficient andsatisfactory for retaining fasteners in driivng position on the bit 60.

In FIGS. 10 and 11 there is shown a further embodiment of the inventionas applied to an elongated screw driver shank in which the magnetassembly is slidably mounted on the shank of the screw driver forretaining a threaded fastener in spaced relation to the end of the screwdriver initially, while permitting the screw driver to move intooperative engagement with the fastener while retaining the fastener inposition. In this embodiment, the screw driver is shown as including anelongated shank with a driven end 81 thereon adapted to be receivedwithin a suitable socket. The forward end of the shank 80 is tapered andforms a screw driving blade 82.

A magnet assembly 85 is shown as being mounted over the shank 80 forlimited axial movement thereon. For this purpose, the shank 80 isprovided with an annular groove 86 and a snap ring 87 therein. Theassembly 85 includes an outer sleeve 90 with an inner snap ring 92 atthe rearward end thereof engageable with the ring 87 to limit the extentof forward movement of the assembly 85 on the shank 80-. The sleeve 85may be further provided with a snap ring stop 92, and a spring 94 isreceived within the sleeve 85 in compression between the stop 92 and thering 97, to urge the assembly 85 forwardly, as shown in FIG. 10.

The magnet assembly 85 further includes an inner sleeve 95 which isconcentric with the sleeve 85 and which is received generally at theforward end thereof and which terminates at a forward end 96. The end 96is spaced axially inwardly of the forward end of the sleeve 85. Thematerial 20 is shown as being received in the annular space between thesleeves 95 and 85, and is spaced slightly inwardly of the forward end96, as shown at 98 in FIG. 10.

The embodiment of FIG. 11 is similar to that of FIG. 10 except that itshows a construction which is particularly adapted for use withfasteners of small size. In this embodiment, the sleeve 85 supports atits forward end an auxiliary pole piece member 100 which, as shown,comprises an annular sleeve with an inwardly turned end 102. Theinwardly turned end 102 is thus proportioned to engage thecircumferential edge of the fastener 105 while the inner sleeve 95engages the face of the fastener. Alternatively, the sleeve 85' may bemolded or formed with an inwardly turned ledge so as to engage thefastener 105.

It will therefore be seen that this invention provides a compact andhighly efficient magnetic tool and magnet assembly for such tools. Thetool body itself may be utilized as one of the pole pieces or separateannular concentric pole pieces may be provided. The thickness-orientedmagnetic material utilizes a minimum of space while maximum utilizationis made of the magnetic properties thereof.

While it is preferred that the material of the magnet 29 be formed offlexible material, as described above, and magnetized through itsthickness, it is within the scope of this invention to use cylindricalmagnets of other compositions, such as, for example, barium ferriteceramic which are similarly thickness-oriented with respect to magneticpoles. The term thickness-oriented magnetized material as used herein isintended to refer to any such suitable material formed either flat andsubsequently rolled or curved as by form-ing or bending, or formedinitially as an annulus or sleeve.

While the forms of apparatus herein described constitute preferredembodiments of the invention, it is to be understood that the inventionis not limited to these precise forms of apparatus, and that changes maybe made therein within departing from the scope of the invention whichis defined in the appended claims.

What is claimed is:

1. A rotatable magnetic tool for picking up magnetically attractablethreaded fasteners and retaining such fasteners in a driving positionthereon and for rotatably driving such fasteners, comprising a tool bodyhaving a fastener driving portion, means forming a pair of spacedapartgenerally annular pole pieces having terminal ends adjacent the drivingportion of said body and defining an annular space therebetween with atleast one of said pole pieces being proportioned to engage a fastenerthereby and magnetically retain said fastener in said driving position,and an annular thickness-oriented elastomeric strip magnet received inthe said annular space between said pole pieces forming oppositemagnetic poles at the said terminal ends.

2. The tool of claim 1 in which one of said pole pieces includes saidtool body.

3. The tool of claim 1 in which said tool body comprises a screw driverbit, and in which said magnet is supported in circumferential relationto the bit adjacent the driving end thereof.

4. The tool of claim 1 in which said tool driving portion comprises asocket wrench having means in said body forming an axial opening, saidmagnet being received in said opening, and one of said pole pieces beingformed as a tubular sleeve received within said magnet and defining abolt clearance space therein in generally axial alignment with thedriving portion of said tool.

5. The tool of claim 1 in which said pole pieces comprise a pair ofconcentric tubular sleeves received on said body.

6. The tool of claim 1 in which said pole pieces comprise a pair ofconcentric sleeves, means closing the annular space between said sleevesat an end thereof remote from said tool driving portion, and meansslidably mounting said pole pieces on said body.

7. A magnetic pick up socket wrench for picking up and drivingfasteners, nuts and the like com-prising a body, 5

means adjacent one end of said body forming a driving portion ofnon-cricular outline for engaging such fastener and further defining anaxial bore within said socket body,

an annular strip of elastomeric thickness-oriented magnetic materialreceived in said socket body inwardly of said driving portion, and agenerally tubular pole piece received in said body radially inwardly ofsaid strip and forming a relatively close fit with said strip with aforward portion thereof positioned in said driving portion to engage afastener therein and defining an axial clearance opening therethrough.

8. A magnetic pick up screw driver comprising a driving bit having aplurality of screw driving wings formed on one end thereof, a screwretaining magnet assembly on the body of said bit including an innersleeve forming a first pole piece and an outer sleeve forming an outerpole piece and defining an annular space therebetween, a strip ofthickness-oriented magnetized material received in said annular space insurrounding relation to said first pole piece, means on said first polepiece for gripping said bit body and retaining said magnet assemblythereon, and the forward edges of said pole pieces forming oppositeannular magnet poles and being proportioned to engage a fastener andretain the same in driving position on said bit.

9. A rotatable magnetic tool for picking up magnetically attractablethreaded fasteners and for retaining such fastensrs in a drive positionthereon and for rotatably driving such fasteners comprising ,a tool bodyforming a screwdriver bit having a driving end, means forming a pair ofspaced apart generally concentric pole pieces with said bit body formingthe inner of said concentric pole pieces said concentric pole piecesdefining an annular space therebetween with said bit driving end beingproportioned to engage a fastener thereon and magnetically retain saidfastener in said driving position, and an annular thicknessorientedelastomeric strip magnet received in said annular space between saidpole pieces forming opposite magnetic pole-s at said pole pieces withsaid driving end of said bit extending beyond the end of said stripmagnet.

References Cited UNITED STATES PATENTS 2,864,417 12/1958 Scholten 7-12,999,275 9/ 1961 Blu-me 156243 3,007,504 11/1961 Clark --50 3,253,2625/1966 Stillwagon, et a1. 145-50 FOREIGN PATENTS 1,266,884 6/ 196-1France.

ROBERT C. RIORDON, Primary Examiner. WILLIAM FELDMAN, Examiner.

R. V. PARKER, IR., Assistant Examiner.

